Reduction of fuel cell cathode potential at startup and shutdown

摘要

Each cell of a fuel cell stack is provided, between the anode 37 and cathodes 38 , with either (a) a permanent shunt ( 20 ) which may be a discrete resistor ( 42-44 ), a diode ( 95 ), a strip of compliant carbon cloth ( 65 ), or a small amount of conductive carbon black ( 22 ) in the ionomer polymer mixture of which the proton exchange membrane ( 39 ) is formed, or (b) a removeable shunt such as a conductor ( 69 ) which may be rotated into and out of contact with the fuel cell anodes and cathodes, or a conductor ( 85 ) which may be urged into contact by means of a shape memory alloy actuator spring ( 90, 91 ), which may be heated.